Having much of my boat torn up and exposed at the moment (1990 Mark 1.25), the best area for additional tankage seems to be the bow area under the V-berth. The space under the aft berth isn't very big and also nice to have access to engine cabling,wire runs, muffler, and shaft log.
Getting rid of my marine head and holding tank, as well as the aft water tank, has me thinking about replacing the old holding tank with a new Ronco 30 gallon fresh water tank. They can be bought new off the shelf for a few hundred $ and slot right in. I dislike the crowding to the quadrant and access to the aft thruhulls/hoses presented by the aft water tank (I recently removed it to replace cockpit scupper hoses and engine exhaust hose, and have left it out.) So I am seriously considering conversion of that space for items that are needed for the shorter term and which can be removed easily for any maintenance items back there.
Also, having had the Galley floor removed and cutting into the floor to run new wires directly to the engine--eliminating the old wiring through the panel switch--I can say there is not a lot of room there for integral tanks.
Again, for me, this is all made possible by the decision to remove the marine head and holding tank in favor of a porta-potti/Airhead composting head. No regrets there at all. But I'm also not the kind of owner likely to attempt integral tankage, preferring the modular tankage which is relatively easy to install--and replace-- in our boats. Even if I put in a new Port settee Ronco water tank, I still have a fair amount of space to work with (1) under the V-berth and (2) made available with the removed aft water tank.
Like Kevin, I've put in a flexible bladder tank in a prior boat. But I didn't love the taste of the water from that water bladder, or the way it shifted in the hull space. So I don't think I'd do that again.
Patches
